Electric odometer drive

ABSTRACT

An electrically operated odometer including an electric motor, a plurality of odometer rolls and reduction gearing preferably in the form of series connected worm and worm gear sets coupling the electric motor to the odometer rolls. A plastic housing completely encloses the electric motor and the reduction gears with the housing being positioned in spaced relationship to the electric motor. The electric motor is alternately energized and de-energized by suitable switching arrangements to drive the odometer rolls, and the reduction gearing provides high torque and minimum overrun on the odometer rolls.

O United States Patent 11 1 3,659,780

Woodward 1 May 2, 1972 [541 ELECTRIC ODOMETER DRIVE 1,269,399 6/1961Germany ..324/l67 Inventor: y Floyd Woodward, Ann Arbor Mich. 597,579 l/1948 Great Britain ..324/l67 [73] Assignee: Ford Motor Company,Dearborn, Mich. Primary Examiner-Richard R. Wilkinson AssistantExaminer-Stanley A. Wal [22] Filed 1970 Attorney-John R. Faulkner andKeith L. Zerschling [21] Appl. No.: 93,598

[57] ABSTRACT [52] U.S. Cl. ..235/95 R, 324/ 167 An electricallyoperated odometer including an electric mo- [51] tor, a plurality ofodometer rolls and reduction gearing [58] Field of Search ..235/95,96;324/167 preferably in the form of series connected worm and worm gearsets coupling the electric motor to the odometer rolls. A [56]References Cited plastic housing completely encloses the electric motorand the reduction gears with the housing being positioned in spacedUNITED STATES PATENTS relationship to the electric motor The electricmotor is all,055,91 l 3/1913 Hopkins ..324/167 temately energized andde-energized by suitable switching ar- 1,364,673 1/1921 Wood ..324/l67 rng -m to drive the odometer rolls, and h r ction 2,339,743 l/ 1944Norman ..324/l67 gearing provides high torque and minimum overrun on the3,166,245 1/1965 Maschke ..235/95 odometer rolls. 3,309,609 3/1967Brewer et al ..324/l67 g 5 Claims, 7 Drawlng Figures FOREIGN PATENTS ORAPPLICATIONS 637,974 11/1936 Germany ..324/167 Patented May 2, 19723,659,780

3 Sheets-Sheet l INVENTOR 6419) f. WOOUW/QPD 4/ ATTOR VS Patented May 2,1972 3,659,780

3 Sheets-Sheet 2 IN VE N TOR M a/wr ff n aoan A/ea A fiym/ v ATTO NEYSELECTRIC ODOMETER nsrvs BACKGROUND OF THE INVENTION This inventionrelates to electrically operated odometers and more particularly to anelectrically operated odometer for an automotive vehicle that is drivenby a small permanent magnet motor through reduction gearing and has verylow noise characteristics.

Electrically operated odometer systems are known which consist of asolenoid ratchet or stepper motor which drives the odometer rolls. Thesolenoid ratchet or stepper motor is pro vided with pulses of electricalenergy from the source of electrical energy through certain switchingmechanisms driven by a portion of the vehicle that rotates at a speedproportional to vehicle speed. These systems have very low output torqueand, hence, are subject to malfunction and binding of the odometer rollsdue to the mechanical tolerances associated with the manufacture of therolls and other associated mechanisms. In addition, these electricallyoperated odometer systems are generally noisy in operation and aretherefore objectionable to operators of automotive vehicles.

In addition, certain other electrically operated odometer systems areknown in the art, but these all suffer from high noise characteristicsand hence are objectionable for use in automotive vehicles.

The present invention provides a very silent and noise free electricallyoperated odometer which has high output torque characteristics and iseasily and inexpensively manufactured and assembled.

SUMMARY OF THE INVENTION The invention provides an electrically operatedodometer including an electric motor preferably of the small permanentmagnet type. This electric motor drives a plurality of odometer rollsthrough reduction gearing which preferably is comprised of two seriescoupled worm and worm gear sets. A plastic housing encloses the electricmotor and the reduction gears to provide low noise characteristics forthe system.

In the preferred form of the invention a metal frame member ispositioned within the plastic housing between the electric motor and thereduction gears. Means are coupled to the electric motor and to theframe for supporting the motor from the frame in a cantilever fashionfrom one end of the motor, and the housing is spaced from the motor atall other locations.

In addition, a commutator switch arrangement is carried by the reductiongearing. This commutator switch arrangement has contacts engaging thecommutator and connected in circuit with the electric motor. A source ofelectrical energy is connected to the motor and the motor is in turnconnected to this commutator. A switching arrangement preferably in theform of a similar commutator is driven by a rotating part of the vehiclethat rotates at a speed proportional to vehicle speed. These switchesare operated at the same speed and sequentially energize the motor withpulses of electrical energy.

The reduction gearing is supported by the frame member mentioned aboveand the reduction ratio is preferably very high, for example, on theorder of 500 to I, so that the odometer rollsare driven with a very hightorque. In addition, with the use of the two sets of worm and worm gearsconnected in series, the system stops almost instantaneously (nooverrun) when the motor is de-energized.

Thus, the present invention provides an electrically With the switchingof the motor periodically to energized and de-energized states, the highpitched noise associated with high speed electric motors is not presentexcept at very high automobile vehicle speeds, At these speeds the othervehicle noise, such as, road and wind noise, is sufficiently high thatthis high speed whine is masked and is not objectionable.

The invention will now be described in connection with the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view partially insection of the electrically operated odometer of the present invention,

FIG. 2 is a side elevational view, partially in section, of theelectrically operated odometer of the present invention,

FIG. 3 is a sectional view taken along the lines 3-3 of FIG.

FIG. 4 is a sectional view taken along the lines 4-4 of FIG. 1 r

FIG. 5 is a perspective view of the commutator employed with the presentinvention,

FIG. 6 is a circuit diagram of the electrical system employed with thepresent invention, and

FIG. 7 is a sectional view of the sender or sensor employed with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings inwhich like reference numerals designate like parts throughout theseveral views thereof, there is shown in FIGS. 1 through 4 theelectrically operated odometer 10 of the present invention whichcomprises generally a permanent magnet electric motor 12 connected to aplurality of odometer rolls 14 of conventional construction throughreduction gearing 16. The permanent magnet motor 12 and the reductiongearing 16 are enclosed in a plastic housing18 which includes agenerally cup shaped portion 20 with an end wall 22. The innerdimensions of the cup shaped portion 20 of this plastic housing 18 areslightly larger than the outer dimensions of the permanent magnet motor12 so that the motor may be positioned in spaced relationship to the cupshaped portion 20 as can best be seen by reference to FIGS. 1 and 3.

The end of the plastic housing 18 opposite the end wall 22 i has anaxially extending portion or wall 24 which is open at the end thereof.This end may be closed by a plastic end wall 26 to form an enclosed gearchamber 28 for enclosing the reduction gearing 16.

- A metal frame member 30 has a generally flat body portion 32 securedto the plastic housing member 18 at a point intermediate the permanentmagnet motor I2 and the rereduction gearing 16 by a plurality of screws,one of which is shown at 34. A pair of ears or tabs 36 and 38 extendperpendicularly from the flat body portion 32.

The permanent magnet motor 12 is supported in cantilever fashion fromthe body portion 32 of the frame 30 by means of a metal guide 40 whichis suitably secured in an aperture positioned in the body portion 32 ofthe frame 30. The distance between the body portion 32 of the metalframe 30 and the end wall 22 of the plastic housing 18 is such that theend of the I permanent magnet motor 12 opposite the metal frame 30 isoperated odometer which has very low noise characteristics positioned inspaced relationship to the end wall 22 of the housing 18 as can best beseen by reference to FIGS. 1 and 2.

The reduction gearing 16 comprises a pair of worm and worm gear sets 42and 44 as can best be seen by reference to FIG. 3. The worm of the firstworm and gear set 42 is designated by the numeral 46, and as can best beseen by reference to FIG. I, this worm 46 is formed on the end ofarmature shaft 47 of the permanent magnet motor 12. The worm gear 48 ofthe first worm and gear set 42 is formed on a cross shaft 50 and thiscross shaft 50 is rotatably, supported through suitable bearings, in theears or tabs 36 and 38 of the frame 30. This cross shaft 50 also has theworm 52 of the second worm and gear set 44 formed thereon.

The worm gear 54 of the second worm and gear set 44 is rotatablysupported at one end from the body portion 32 of the frame member 30 bymeans of a journal or hearing 56. A shaft 58 extends from the other endof the worm gear 54 and it is employed to drive the odometer rolls 14.

The odometer rolls 14 are supported generally in a U- shaped metal frameor support structure 60 having a central portion 62 and a pair of legs64 and 66 extending at right angles thereto. The odometer rolls 14 havea shaft 68 extending outwardly therefrom in alignment with the shaft 58which is driven by the worm gear 54 of the second worm and gear set 44.

The leg 66 of the metal frame 60 and the end wall 26 of the plastichousing 18 are secured to the plastic housing 18 by means of a pluralityof screws 72 as shown in FIGS. 2, 3 and 4. A generally rectangularrubber insulator member (not shown) may be positioned between the endwall 26 of the plastic housing 18 and the leg 66 of the frame 60 foradditional noise isolation purposes.

The worm 46 and the worm gear 48 of the first worm and gear set 42 aswell as the worm 52 and the worm gear 54 of the second worm and gear set44 are all formed of plastic material as is the balance or remainder ofthe cross shaft 50. It is to be understood, however, that the shaftsthat support these gears. in the frame 30 may be formed of suitablemetal and that these gears including the cross shaft 50 may be suitablyafiixed to these metallic shafts. This construction provides for a verysilent operating gear set with minimum backlash and overrun.

A commutator 80 which is shown in perspective in FIG. is positioned onan undercut portion of the end of cross shaft 50 opposite the worm 52 ofthe second worm and gear set 44 and adjacent to the worm gear 48 of thefirst worm and gear set 42. This commutator may be in the form of ametal sleeve which has a first portion 82 formed in a complete cylinderand a second portion 84 formed in a partial cylinder, slightly more thanone-half a cylinder. As a result when this commutator 80 is positionedon the plastic cross shaft 50 the full cylindrical portion 82 ispositioned adjacent the ear or tab 38 of the metal frame member 30 ascan best be seen by FIG. 2 and the partial cylindrical portion 84 ispositioned adjacent the worm gear 48.

A pair of contacts in the form of wires 86 and 88 engage the fullcylindrical portion 82 of the commutator 80 and these wires are in turnconnected in parallel to a terminal 90. Two wire contacts 92 and 94 areconnected in parallel to a terminal 96 and are positioned to engage thepartial cylinder 84 of the commutator 80. Two other 'wire contacts 98and 100 are positioned in opposed relationship to the two wire contacts92 and 94 and these contacts are connected in parallel to a terminal102. These two wire contacts 98 and 100 are also positioned Y to engagethe partial cylinder 84 of the commutator 80.

A source of electrical energy, preferably in the form of an electricalstorage battery for the automotive vehicle utilizing the presentinvention has its positive terminal connected to a terminal 106positioned in the permanent magnet motor 12. Referring now to FIG. 6,this source of electrical energy is designated by the symbol 8+ and thepositive terminal thereof is connected through lead 108 to the terminal106 of the permanent magnet motor 12. The terminal 106 is in turnconnected to an armature brush 110. The other armature brush 112 isconnected to the terminal 90 which is adapted through wires 86 and 88 tobe in constant engagement with the cylindrical sleeve 82 of thecommutator 80. The stationary contacts 92-94 and 98-100 are shown onthis drawing and through the partial cylinder 84 of the commutator 80,the contacts 92-94 and 98-100 are alternately connected to the contacts84-86 and hence terminal 90 as the cross shaft 50 is rotated by means ofthe reduction gearing 16.

A sender 114, shown schematically in FIG. 6, is shown in cross sectionin FIG. 7. This sender comprises a housing 116 having a shaft 118rotatably mounted therein. This shaft is adapted to be driven by arotating part of the vehicle that rotates at a speed proportional tovehicle speed, for example,

an output gear on the vehicle transmission. This shaft 118 includes aworm 120 of a worm and gear set 122. The worm gear 124 of the worm andgear set 122 is carried on a cross shaft 126 which is rotatablymountedwithin the housing 116. This cross shaft also has positioned thereon acommutator 130 which is similar in form to the commutator 80 positionedon the cross shaft 50 of the electrically operated odometer 10.

This commutator includes a full cylindrical sleeve 132 and a partialcylindrical sleeve 134, less than one-half a cylinder. A wire contact136 contacts the full cylindrical sleeve 132 and a pair of opposed wirecontacts 138 and 140 engage the partial cylindrical sleeve 84 and theplastic material of the commutator 130.

As shown in FIG. 6 the contact 136 is connected to ground or the housing116 through a lead 142, while contact 138 is connected to terminal 96 ofthe electrically operated speedometer 10 through a lead 144 and thecontact 140 is connected to terminal 102 through a lead 146.

As stated previously, the reduction gear set 16 has a high gearreduction ratio or high speed reduction ratio coupled with itscomplementary high torque multiplication ratio. For example, the speedreduction ratio and the torque multiplication ratio of the reductiongear set 16 may be on the order of 500:1 to 750:1. As an example, thefirst worm and worm gear set 42 may have a speed reduction ratio andtorque multiplication ratio of 10 to 1, while the second worm and wormgear set 44 may have a speed reduction ratio and torque multiplicationratio of 50:1 thereby providing an overall speed reduction ratio andtorque multiplication ratio of 500:1. As disclosed, the speed reductionratio of the worm and worm gear set 122 employed with the sender 114 isthe same as the speed reduction ratio of the first worm and worm gearset 42 of the electrically operated odometer 10. This need not be thecase, however, but it has been found that a speed reduction ratio offrom 10: 15 in the worm and gear set 122 works very well.

In operation, if it is assumed that the commutator is positioned asshown in FIG. 6 so that the partial cylindrical sleeve 84 is in contactwith the wire contacts 92 and 94, the permanent magnet motor 12 will beenergized when the shaft 118 rotates sufficiently to bring thecommutator 130 into the position shown in FIG. 6 where the partialsleeve 134 is in contact with the contacts 138. In this instance acircuit is completed from the source of electrical energy through thebrushes and 112 of permanent magnet motor 12, terminal 90, contacts86-88, commutator 80, contacts 92-94, terminal 96, lead 144, contact138, commutator 130, contact 136 and lead 142 to ground. This causes thepermanent magnet motor 12 to rotate thereby rotating the reductiongearing 16 and driving the odometer rolls 14 at the speed reductionratio of 500:1 in the example given At the same time the motor 12 drivesthe cross shaft 50 and the commutator 80 at a 10:1 speed reductionratio. When the commutator 80 has been driven sufficient distance tobring the partial sleeve 84 out of engagement with the contacts 92, 94the circuit is broken to the pennanent magnet motor and the system willbe de-energized. This will occur, of course, at the junction of thepartial sleeve 84 and the plastic material located on the cross shaft 50and the partial sleeve will be in engagement now with the contacts 98,100. The shaft 118 will continue to rotate at the speed proportional tovehicle speed and will therefore continue to drive the commutator 130.When the partial sleeve 134 of the commutator comes into contact withthe contact a circuit will again be completed through the pennanentmagnet motor from the source of electrical energy. In this instance, thecircuit is completed through contacts 98, 100 on commutator 80, terminal102, lead 146, contact 140, the partial sleeve 134 on commutator 130,commutator 130, contact 136 and grounded lead 142. The permanent magnetmotor will then rotate for five revolutions until the partialcylindrical sleeve 84 comes out of contact with the contacts 98-100.This is true since the permanent magnet 12 makes 10 revolutions forevery revolution of thecommutator 80 due to the 10:1 speed reductionratio of the first worm and wonn gear set 42. At this time the motorwillbe de-energized and the contacts 92-94 will be in contact with thepartial cylindrical sleeve 84. As the shaft 118 continues to rotate itwill drive the commutator 130 until the partial cylindrical sleeve 134of commutator 130 is again in contact with the contacts 138. A circuitthrough the permanent magnet motor 12 will then again be completedthrough the circuit previously described including contacts 92-94,terminal 96, lead 144, contact 138, commutator 130, contact 136 and lead142 to ground.

The above cycle will repeat continuously as long as the shaft ll8 of thesender 114 is rotated by the automotive vehicle. The duty cycle of thepulses of electrical energy applied to the electric motor 12 and hencethe duty cycle of the electric motor increases as a function of vehiclespeed.

The timing of the commutator 80 and its associated contacts 98-100 and92-94 is much faster than the timing of the sender or speed sensor 114comprised of the commutator 130 and the associated contacts 138 and 140so that at all speeds of the automotive vehicle the commutator 80 andits associated switching structure leads the commutator 130 and itsassociated switching structure's. Consequently, the commutator 130 ofthe sender 1 14 always completes the circuit to energiae the motor 12,and the commutator 80 of the electrically operated odometer l alwaysbreaks the circuit to de-energize the motor 12.

Although forming no part of the present invention, the sender 114 mayhave associated therewith a photocell 150 and a light emitting device inthe form of a light emitting diode 152.

A shutter 154 in the form of an open ended cylinder is affixed to theshaft 118 and is positioned betwen the photocell 150 and the lightemitting diode 152. This shutter has a plurality of apertures 156positioned therein. As the shaft 118 rotates at a speed proportional tovehicle speed the photocell is alternately energized and de-energizedfrom the light emitting diode 152 as the apertures l56-pass betweenthem. The output from the photocell is therefore a waveform having afrequency which is proportional to vehicle speed. This signal may besuitably processed to provide a readout of vehiclespeed in a displaydevice positioned on the instrument panel and in close proximity to theodometer rolls 14 of the present invention.

It can be readily appreciated from the above description and examinationof the drawings that the permanent magnet motor 12 and the plasticreduction gearing 16 are completely enclosed within the plastic housing18 and that the permanent magnet motor 12 is spaced from the plastichousing 18 over substantially all of its periphery. This constructionprevents noise both in the permanent magnet motor and in the reductiongearing from being transferred outside the housing 18 where it could beheard by the vehicle operator. in addition, the present inventionprovides a very high torque multiplication gear set which will providevery high torques on the odometer roll thereby facilitating easyoperation and less jamming of these rolls than is known in current lowtorque odometer systems. Moreover, becauseof the two worm gear setsconnected in series, the odometer rolls will stop almost instantaneouslywith no overrun when the power to the electric motor is terminated. Thisparticular feature allows the system to be operated in the pulse modetype of operation described above through any normal vehicle speedincluding speeds up to miles per hours.

lclaim:

1. An electrically operated odometer comprising, an electric motor, aplurality of odometer rolls, reduction gears coupling said electricmotor to said odometer rolls, a plastic housing enclosing said electricmotor and. said reduction gears, a metal frame member positioned in saidhousing between saidelectric motor and said reduction gears, saidreduction gears including a pair of worm and worm gear sets connected inseries, said electric motor including an armature shaft extendingthrough said frame, the worm of said first worm and gear set positionedon said armature shaft, a cross shaft rotatably mounted in said frame,said cross shaft having the worm gear of said first worm andgear set andthe worm of said second wonn and gear set positioned thereon, saidodometer rolls having an odometer shaft extending in parallelrelationship to said armature shaft, one end of said odometer shaftrotatably mounted in said frame, the worm of said second worm and gearset positioned on said odometer shaft, and means coupled to saidelectric motor and said frame for supporting said motor from said framein cantilever fashion from one end of said motor, said housing beingspaced from said motor at all other locations.

2. The combination of claim 1 in which the speed reduction ratio of saidpair of worm and worm gear sets is in the range of about 500: l to750:1.

3. The combination of claim 1 and comprising further a commutatorcarried by said cross shaft and contacts engaging said commutator andconnected in circuit with said electric motor.

4. The combination of claim 3 in which said commutator in cludes meansenergizing said motor during each half revolution of said cross shaft.

5. The combination of claim 1 in which said plastic housing has agenerally cup shaped portion with an integrally formed end wallreceiving said electric motor, the inner dimension of said cup shapedportion being slightly greater than the outer dimension of said electricmotor and the length of said cup shaped portion being slightly greaterthan the length of said electric motor.

i l 1% i l

1. An electrically operated odometer comprising, an electric motor, aplurality of odometer rolls, reduction gears coupling said electricmotor to said odometer rolls, a plastic housing enclosing said electricmotor and said reduction gears, a metal frame member positioned in saidhousing between said electric motor and said reduction gears, saidreduction gears including a pair of worm and worm gear sets connected inseries, said electric motor including an armature shaft extendingthrough said frame, the worm of said first worm and gear set positionedon said armature shaft, a cross shaft rotatably mounted in said frame,said cross shaft having the worm gear of said first worm and gear setand the worm of said second worm and gear set positioned thereon, saidodometer rolls having an odometer shaft extending in parallelrelationship to said armature shaft, one end of said odometer shaftrotatably mounted in said frame, the worm of said second worm and gearset positioned on said odometer shaft, and means coupled to saidelectric motor and said frame for supporting said motor from said framein cantilever fashion from one end of said motor, said housing beingspaced from said motor at all other locations.
 2. The combination ofclaim 1 in which the speed reduction ratio of said pair of worm and wormgear sets is in the range of about 500:1 to 750:1.
 3. The combination ofclaim 1 and comprising further a commutator carried by said cross shaftand contacts engaging said commutator and connected in circuit with saidelectric motor.
 4. The combination of claim 3 in which said commutatorincludes means energizing said motor during each half revolution of saidcross shaft.
 5. The combination of claim 1 in which said plastic housinghas a generally cup shaped portion with an integrally formed end wallreceiving said electric motor, the inner dimension of said cup shapedportion being slightly greater than the outer dimension of said electricmotor and the length of said cup shaped portion being slightly greaterthan the length of said electric motor.